In case someone needs it, this is modified 'ethkey' build for linux, zip contains also modified file - so anyone can just compile entire github resource with replacing one file in ethkey dir.
ethkey --inspect-bare UID
etykey --inspect-bare file
To extract key.
It works with eth++ keystores. In case geth, you need to slighlty modify json format to proceed. Just compare both and modify geth to match cpp version.
then you can simply migrate key from geth or eth to new wallet of eth++ or just publish your secret key anywhere you want